The double-spotted line blue (Nacaduba biocellata) is a butterfly of the Lycaenidae family. It is found in Australia (including New South Wales, the Northern Territory, South Australia, Victoria and Western Australia), Singapore, the New Hebrides, Sumba and Bali. The wingspan is about 20 mm. Adult females have a brown upperside, while the males are blue with narrow black margins. The underside of both sexes is pale brown with light and dark wavy lines. Pupation takes place in a pale brown pupa, which is formed in debris on the ground under the food plant.